Conventionally known typical resist materials are polymer based materials capable of forming amorphous thin films. For example, a line pattern of about 45 to 100 nm is formed by coating a substrate with a solution of a polymer resist material such as polymethyl methacrylate, polyhydroxy styrene with an acid dissociation reactive group, or polyalkyl methacrylate to prepare a resist thin film and then irradiating the resist thin film with ultraviolet, far ultraviolet, electron beam, extreme ultraviolet (EUV), and X-ray or the like.
However, polymer based resists have a molecular weight as large as about 10,000 to 100,000 and also wide molecular weight distribution. Therefore, in lithography using a polymer based resist, roughness occurs on a fine pattern surface; the pattern dimension becomes difficult to be controlled; and the yield is decreased. Therefore, there is a limitation in miniaturization with lithography using a conventional polymer based resist material. Then, in order to make a finer pattern, various low molecular weight resist materials have been proposed.
For example, an alkaline development type negative type radiation-sensitive composition (see Japanese Patent Application Laid-Open No. 2005-326838 and Japanese Patent Application Laid-Open No. 2008-145539) using a low molecular weight polynuclear polyphenol compound as a main component has been suggested. Additionally, as a candidate of a low molecular weight resist material having high heat resistance, an alkaline development type negative type radiation-sensitive composition (see Japanese Patent Application Laid-Open No. 2009-173623 and T. Nakayama, M. Nomura, K. Haga, M. Ueda: Bull. Chem. Soc. Jpn., 71, 2979 (1998)) using a low molecular weight cyclic polyphenol compound as a main component has also been suggested.
As a base compound of a resist material, a polyphenol compound is known to be useful in imparting high heat resistance and improving the resolution or roughness of a resist pattern, in spite of its low molecular weight (see Shinji Okazaki et al., “Innovation of Photoresist Material Development”, CMC Publishing Co., Ltd., September 2009, p. 211-259).